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For this topic, the specification states that you should know the following:
There are 3 main factors that affect the performance of a CPU.
These factors are:
The clock speed refers to the amount of fetch-execute cycles that can be run per second.
Clock speed is measured in Hertz (Hz).
More modern process operate at billions of cycles per second, which is measured in Gigahertz (GHz).
For example, a processor with a 2.5GHz clock speed can perform 2.5 billion fetch-execute cycles per second!
With a higher clock speed, you can expect better performance.
Cache is a small area of high-speed memory located in the CPU.
It is used for temporary storage of data and instructions currently in use.
Copies of recent data and instructions are stored temporarily in the cache to make it quicker to use them again if needed.
It is much quicker to fetch data from the cache than from main memory (RAM). Where possible, we try to avoid getting data from main memory as it takes too much time.
Having a larger cache can lead to better performance.
A CPU is usually made up of multiple processing cores.
A core is essentially a processor inside of a CPU.
Each core has its own processing units.
Since each core is able to process one instruction at a time, having multiple cores would allow a system to process multiple instructions simultaneously.
Having more cores can lead to significantly better performance, especially when multitasking.
However, not all programs are able to make use of multiple cores, therefore the number of cores would not affect the way it runs.
Hi! I'm Oliver, a Computer Science student in the UK. I created CourseNotes as a way to share my learning and knowledge with the world, and help other students to do their best in their exams.
I am currently studying Computer Science at GCSE level with the OCR exam board. All notes on this site will be exam board specific, but a lot of the concepts are similar across other exam boards.
